1. Field of the Invention
The present invention relates generally packet routing systems and more specifically to a method and a system for routing packets without loss of packets when they encounter a fault condition.
2. Description of the Related
In the IP (internet protocol) network, each node of the network includes a router to determine a destination for incoming packets based on routing information stored in a routing table and forwards the packets to the destination, Line cards and associated transmission lines are duplicated to ensure continuity of service against possible faults. Specifically, when a failure is detected in an outgoing transmission line during the time a packet is being routed to that line, the packet is forwarded to the faulty line. The routing table is then updated so that traffic is directed to a duplicated normally operating route. However, during this updating process, packets are still forwarded to the failed route. Because of the delay associated with the table updating process, re-routing cannot be performed instantly when a fault is detected and hence a significant number of packets are lost. In addition, the fault-triggered table updating may represent a substantial amount of burden on the processor, delays are likely to occur in the routinely performed normal task of table updates, which would cause packets to be routed to undesired destinations.